In the case of a machine tool which comprises at least one working spindle with a tool-holding fixture for tool holders carrying tools, and a tool changer with a gripper for the tool holders in order to transfer the tool holders between their magazine position, which is spaced apart from the tool-holding fixture, and their working position in the tool-holding fixture, a clamping system with a clamping apparatus by means of which a tool holder inserted into the tool-holding fixture is fixed is arranged in the working spindle, the clamping system additionally comprising a retaining apparatus for a tool holder situated in the tool-holding fixture. In the case of a method carried out on this machine tool, the clamping system carries out a retaining operation which temporally precedes the clamping operation in order to grasp the tool holder inserted into the tool-holding fixture before the clamping apparatus fixes the tool holder. Furthermore, an unblocking operation which temporally follows the release operation is carried out in order, after the release of the clamping apparatus, still to retain the tool holder in the tool-holding fixture until it is ejected.